Terpolymer of an alpha, beta-unsaturated dicarboxylic acid ester, an alkylene ester and a hydroxyalkyl acrylate, and hydrocarbon oil compositions therewith



United States Patent 3,Z34,l34 Patented Feb. 8, 1966 "ice 3,234,134 TERPOLYMER OF AN oz,/fi-UNSATURATED DICAR- BOXYLIC ACID ESTE AN ALKYLENE ESTER AND A HYDROXYALKYL ACRYLATE, AND HY- DROCARBON OIL COMPOSITIONS THEREWITH Jack Rockett, Westfield, N.J., and Richard P. Crowley,

Milton, Mass., assignors to Esso Research and Engineering Company, a corporation of Delaware No Drawing. Filed Sept. 7, 1962, Ser. No. 222,223 8 Claims. (Cl. 252-56) case lubricants, has long been recognized. Heretofore,

detergency and sludge dispersancy have been obtained in lubricating oil compositions by incorporating therei n metal-containing additives, as for example alkaline earth metal organic sulfonates, metal alkyl phenates, metal alkyl phenol sulfides, and the like. Such additives have a disadvantage in high performance internal combustion engines, however, in that they promote the formation of ash residues in the combustion chamber. Such ash resi-. dues cause preignition, spark plug fouling, valve burning, and similar deleterious conditions. Accordingly, detergent and dispersant additives for crankcase lubricants that are either entirely ash-free or are at least relatively low in ash-forming tendencies are particularly desirable. Metal-free additives that have multifunctional characteristics, i.e., those that furnish viscosity index improving and pour point depressing properties in addition to detergency and sludge dispersancy, are particularly advantageous.

In accordance with the present invention, it has been found that lubricating-oil-soluble additives that have the multifunctional properties of viscosity'index improvement, pour point depressancy, and sludge dispersancy can be prepared by copolymerizing hydrozyalkyl acrylates with other polymerizable esters. The hydroxyalkyl acrylates may be represented by the formula, I

wherein R is selected from the group consisting of hydrogen; methyl, and ethyl radicals, R" is an alkylene hydrocarbon group of from 2 to 6 carbon atoms, and n is an integer of from 1 to 5. Specific examples of such compounds include hydroxyamyl acrylate, hydroxyethyl ethacrylate, hydroxypropyl methacrylate, hydroxyethyl methacrylate, and 2,3-dihydroxypropyl methacrylate.

. It is particularly preferred that the hydroxyalkyl acrylates be copolymerized with two types of esters, one being an ester of a C to C aliphatic alcohol and an alpha, beta-unsaturated dicarboxylic acid, and the other ester being an alkylene ester of a short chain aliphatic carboxylic acid. The preferred alpha, beta-unsaturated dicarboxylic acidis fumaric acid, although may be used. The alkylene esters include vinyl, isopropenyl, and allyl esters of short chain fatty acid such as acetic, proprionic and butyric acids, such as vinyl acetate,-

vinyl propionate, allyl acetate, isoprope-nyl acetate, and vinyl butyrate.

h The: broad and preferred ranges of molar proportions maleic acid or itaconic acid solvent, and temperatures may range of the monomers employed in preparing the tripolymers of the invention are as follows:

Mole percent in terpolymer Component Broad Preferred range range Hydroxyalkyl acrylate 1-10 2-5 Ahphatie ester of alpha, beta-unsaturated diearboxylie acid 15-50 20-30 Alkylene ester of short chain fatty acid 50-85 -80 Specific examples of aliphatic alcohol esters of alpha, beta-unsaturated dicarboxylic acids that may be used in this invention include octyl itaconate, octadecyl maleate, lauryl fumarate, lauryl maleate, tallow maleates, oleyl fumarate, allyl fumarate, tallow fumarates, C or C oxo fumarate. Esters of glycol monoalkyl ethers and fumaric or maleic acids may also be used, as for example, cellosolve furnarate (glycol monoethyl ether fumarate).

By tallow furnarates or m'aleates is meant the esters I of fumaric acid or maleic acid and the alcohols derived by hydrogenation of tallow. The latter are'principally C and C1 alcohols, with minor amounts of C12, C and C alcohols. The oxo alcohols are well known in the art and are prepared from olefins by reaction with carbon monoxide and hydrogen in the presence of a suitable catalyst such as one containing cobalt, e.g., a cobalt carbonyl. The reaction products are primarily aldehydes having one more carbon atom than the starting olefins. These aldehydes are then hydrogenated in a separate catalytic stage to convert them to the corresponding alcohols.

The tripolymers of the present invention may be prepared by any well-known polymerization process, including low temperature Friedel-Crafts polymerization, ionic polymerization processes, or radiation polymerization processes. Free radical catalysts, for example peroxide type catalysts, are particularly useful. These include benzoyl peroxide, acetyl peroxide, urea peroxide, and tertiary butyl perbenzoate. A hydroperoxide or an azo catalyst such as alpha, alpha'-azo-bis-isobutyronitrile may be used. These catalysts may be employed in concentrations in the rangeof from about 0.01 to about 2 weight percent. The polymerization may be carried out in a suitable solvent in order to control reaction velocity and molecular weight. Oxygen may be excluded during the polymerization by the use of a blanket of an inert gas such as nitrogen or carbon dioxide. Solvents include benzene, heptane, mineral oil or other suitable organic from about to about 230 F. and reaction times may vary from about 3 to 7 hours. The final tripolyrner may have a molecular weight in the range of from about 50,000 to about 600,000 or higher. The molecular weight can be determined by measuring the viscos1ty of solutions containing 5 milligrams of the copolymer per co. in diisobutylene and applying the Staudinger equation. Molecular weights of from about 100,000 to about 500,000 are particularly preferred. Upon completion of the polymerization reaction the copolymer may be freed of solvent and employed as an additive for lubricating oils or for fuel oils. For convenience in blending at the termination of the polymerization, the polymer may be diluted with a light mineral oil and then stripped of solvent and unconverted monomers to give a concentrate of the polymer.

r from about 0.1 to about 10 weight percent.

For use as lubricating oil additives for lowering pour point, improving viscosity index and increasing detergency, the tripolymers of the invention may be incorporated in lubricating oil compositions in concentration ranges of The lubricatmoles) of vinyl acetate, 7.1 g. (0.0546 mole) of hydroxyethylmethacrylate, and 1.1 cc. of tert. butyl perbenzoate were added. The mixture was heated to 8590 C. for four hours in a nitrogen atmosphere and then diluted with 250.0 g. of solvent neutral mineral oil.

Example 6 In this example, di-allyl maleate is included as an auxiliary monomer. Into a 2 liter reaction flask were placed 113.2 g. (0.185 mole) of tallow fumarate, 221.8 g. (0.652 mole) of isooctyl fumarate, 1.13 g. of di-allyl maleate, and 83.2 g. of a White mineral oil, and the mixture was heated to 80 C. Then 201.8 g. (2.344 moles) of vinyl acetate, 14.3 g. (0.110 mole) of hydroxyethylmethacrylate, and 2.2. cc. of tert. butyl perbenzoate were added. The reaction mixture was heated and stirred at 85-93 C. in a nitrogen atmosphere for 5 /2 hours, during which time the unreacted fumarate virtually disappeared. The polymer solution was diluted with 500 g. of solvent neutral mineral oil. (150 SSU viscosity at 100 F.)

Example 7 The concentrates of Examples 1 through 6 were each blended in a base oil and the viscosities and viscosity indexes of the base oil and of each of the blends were determined. The base oil consisted of about 60 weight percent of a solvent neutral mineral oil of 100 SSU viscosity at 100 F., about 35 weight percent of a solvent refined naphthenic mineral oil of 400 SSU viscosity at 100 F., and about 5 weight percent of commercial antiwear and detergent additive concentrates. The viscosity index improving properties of the additives are shown in Table I.

The products of Examples 1, 3, 4 and 6 were employed separately as booster detergents in a low-temperature engine test in which conditions were intended to simulate stop-and-go driving. A six-cylinder Ford engine was used, charged with 4 quarts of the oil under test, and run for a total of 242 hours, under the conditions given in Table II, the cycles being repeated until the end of the test.

TABLE II.LOW TEMPERATURE ENGINE TEST CONDITIONS Cycle 1 Cycle 2 Cycle 3 Cycle duration, hours 1. 5 2 2 Engine r.p.m 500 2, 000 2, 000 Air-fuel ratio 11/1 13. 5-14/1 13. 5-14/1 Brake horsepower load- 0 40 40 Torque, pound fect 0 105 105 Oil sump temperature, 180:1:5 18015 215:1;5 Jacket water out temp, F 190:|=5 160:1:5 18015 At the end of the first 66 hours, and every 44 hours thereafter, the engine was inspected by removing the oil pan, the rocker arm cover, and the push rod chamber cover, and various parts including the oil screen, the oil pan, the crankshaft, the push rod chamber, the push rod chamber cover, the rocker arm cover, and the rocker arm assembly, were rated for sludge deposition, using a merit system in which represents a clean part and zero 6 a part covered with the maximum amount of sludge possible.

The test oil consisted of a solvent neutral mineral oil of 170 SSU viscosity at F. containing 1.0 wt. percent of a zinc dialkyl dithiophosphate antiwear additive, 3.5 wt. percent of a commercial detergent inhibitor, and sufficient of the additive concentrate in each case to furnish 2 Weight percent of actual copolymer. (Weight percentages arebased on total composition.)

The detergent-inhibitor used in the test may be characterized as a colloidal complex 0 fphosphosulfurized hydrocarbons, barium alkyl phenate and barium carbonate in mineral oil, prepared by reacting a polyisobutylene of about 940 molecular weight with 15 weight percent P S mixing the product with nonyl phenol and mineral oil and reacting the mixture with barium hydroxide and carbon dioxide at 250-300 F. for 6 to 10 hours to form a product having a representative weight percent composition as follows:

Percent Phosphosulfurized polyisobutene 27.0 Alkyl phenol (248 average molecular weight) 11.7 Barium oxide 10.6 Carbon dioxide 2.5 Mineral oil 48.2

TABLE III.MERIT RATINGS Hours on test 66 154 198 242 Polymer in blend:

Example 1 10.0 9.99 9. 95 9. 85 9. 7 9. 99 9.85 9. 82 9. 2 9. 96 9. 97 9. 96 9. 7 9. 6 9. 98 9. 96 9. 88 9. 85 9. 7 Prior art product 9. 96 9. 8 9. 6 7.1

It is to be understood that the examples presented in the foregoing specification are merely illustrative of this invention and are not intended to limit it in any manner; nor is the invention to be limited by any theory regarding its operability. The scope of the invention is to be determined by the appended claims.

What is claimed is:

1. An improved oil-soluble polymeric additive for mineral oils comprising a polymerization product of an ester of an aliphatic alcohol and an alpha, beta-unsaturated dicarboxylic acid, an alkylene ester of a short chain fatty acid, and a hydroxyalkyl acrylate having the formula,

wherein R is selected from the group consisting of hydrogen, methyl, and ethyl radicals, R" is an alkylene hydrocarbon group of from 2 to 6 carbon atoms, and n is an integer of from 1 to 5.

2. Polymeric additive as defined by claim 1, wherein said hydroxyalkyl acrylate comprises hydroxyl methacrylate.

3. Polymeric additive as defined by claim 1, wherein said hydroxyalkyl comprises hydroxypropyl methacrylate.

4. Polymeric additive as defined by claim 1 wherein said polymerization product constitutes from 1 to 10 mole percent of said hydroxyalkyl acrylate, from 15 to 50 mole percent of said aliphatic ester of an unsaturated 

1. AN IMPROVED OIL-SOLUBLE POLYMERIC ADDITIVE FOR MINERAL OILS COMPRISING A POLYMERIZATION PORDUCT OF AN ESTER OF AN ALIPHATIC ALCOHOL AND AN ALPHA, BETA-UNSATURATED DICARBOXYLIC ACID, AN ALKYLENE ESTER OF A SHORT CHAIN FATTY ACID, AND A HYDROXYALKYL ACRYLATE HAVING THE FORMULA, 